One-pot homogeneous and heterogeneous oxidation of glycerol to ketomalonic acid mediated by TEMPO

Glycerol, an increasingly abundant byproduct of biodiesel production, is selectively converted to ketomalonic acid in one-pot at pH 10 using NaOCl as regenerating oxidant in water at 2 oC in the presence of catalytic Br- along with the radical TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl). The reaction can also be conducted at completion over a sol-gel silica glass doped with the nitroxyl radical. Considering the stability and versatility of such doped glasses, these materials show real promise as reusable metal-free catalysts for the conversion of a readily available and renewable biofeedstock into a highly valued compound.